Pack for electrical heating elements



Apr. 24, 1923.

W. A. BRAUN PACK FOR ELECTRICAL HEATING ELEMENTS Filed April 18, 1922(fil /,4 fl, 11 1/ Patented Apr. 24, 1923.

UNITED STATES I 1,452,954 PATENT OFFICE.

WILLIAM A. BRAUN, or DOVER, orno, ASSIGNOR ro novEn MANUFACTURING coin-PANY, A CORPORATION OF OHIO.

PACK FOR ELECTRICAL HEATING ELEMENTS Application filed April 18, 1922.Serial No. 555,257.

T 0 all whom it may concern:

Be it known that 1, WILLIAM A. BRAUN, a citizen of the United States ofAmerica, and resident of Dover, in the county of Tuscarawas and State ofOhio, have invented certain new and useful Improvements in Packs forElectrical Heating Elements, of which the following is a specification.

This invention relates to improvements in packs for electrical heatingelements, especially for imbedding and insulating resistance wireswithin sad irons and other members to be heated.

In the prior art resistance wires have been used in packs placed inmembers to be heated through the action of electrical current passingthrough the resistance wires, such packs being formed of variousmaterials and compositions of materials. It has been found that suchmaterials and compositions have a tendency to deteriorate rapidlywithuse, and generally, are susceptible to a wide range of insulatingefiiciency, especially at different temperatures. Also, it has beendiflicult to provide packs 01 permanent dielectric properties that havealso the desired capacity for conducting the heat of the resistance wireto the iron or member to be heated. A further difficulty ordinarilyexperienced is when a common pack is used the resistance wire tends tobecome oxidized to a detrimental extent which impairs the wire andreduces its eiiioiency, and it has been sought to overcome thisdifiiculty by making use or" highly refined and expensive metallicresistance members.

The objectsof the present invention are: first, to produce a pack for anelectrical heating member of low hygroscopic and high dielectricproperties, and which also is highly edicient as a conductor of heat;second, to provide a-pack for a resistance wire so constituted as toprevent the resistance wire becoming oxidized; and, third, to provide aneflicient pack for resistance wires that may be constructed and appliedby simple methods and without the usual application of heat atexcessively high temperatures.

The above objects are accomplished by the use or" the materials preparedand applied as hereinafter set forth, the accompanying drawings beingillustrations of a sad iron in which a resistance member is shownimbedded in a pack embodying the present invention, and in which:

Figure l is a plan View of a sad iron partially broken away; and Fig. 2is a longitudinal section projected from Fig. 1.

The characters appearing in the description refer to parts shown in thedrawings and designated thereon by corresponding characters The sad ironshown in the drawings is of usual construction and consists of a base 1and a cover 2 that are secured together by a screw 3. The resistancemember 4 is imbedded in the pack which is composed of a substratum 5 andsuperstratum 6 of cement, there being a cover 2 which afi ords therequired added weight to the iron and serves also to reserve heat.

rhe invention comprises the pack composed of cement that is constitutedof a mixture of refractory material, clay, and boracic acid, in relativeproportions as per the following tabulation:

Percent. Refractory material 83 Clay 12 Boracic aoidfi 5 The refractorymaterial employed is such as alundum fines commonly known in the art, ormay be such other hard granular or pulverulent material of similarcharacter which is possessed of high thermal conductivity and highdielectric properties.

The clay herein used as an agent for holding the pulveruient refractorymaterial suspended in the mixture, may be of any suitable character,such, for example, as Klingenberg clay which has been foundsatisfactory.

The boracic acid when introduced into the mixture is in the form ofpowder.

in preparing the cement, the ingredients 4 is partially imbedded thereinand held in place until the substratum becomes dry and hard. Thesuperstratum 6 of the plastic cement is then formed over the substratumand resistance wire, completely covering the action of the electricalcurrent passing through the resistance wire, which saturates the packduring the initial heating thereof so that the granular particles andthe resistance wire become coated therewith and the interstices betweenthe particles and about the wire become filled, In this manner the packis rendered exceedingly dense and its hygroscopic tendency iscorrespondingly reduced and its dielectric property consequently ispreserved. Also, the intimate coating thus formed upon the resistanceWire .prevents oxidation thereof so that its life is indefinitelyprotracted, and admits of the use of an ordinary and inexpensiveresistance wire.

It has been customary to initially subject packs containing resistancemembers to very intense heat as Well as great pressure for the purposeof increasing the dielectric efficiency of the pack. While such methodsmay improve the insulation afi'orded the resistance member by the pack,the resistance member is impaired by the excessive heat in theoperation. Alm, packs that have been subjected to such excessive heatare more or less pervious and tend to absorb moisture from theatmosphere when not in use, which may occasion leakage or grounding whenthe resistance wire is again charged with electric current. In thepresent invention, however, the initial heating of the pack is carriedout at approximately the ordinary working temperature of the heatingelement without injury, and the pack is rendered practically imperiviousso that absorption of moisture and consequent grounding is obviated.Also, in the present instance, the pack adheres to the resistance wire,and iron in which the pack is formed, without the usual application ofgreat pressure, and the ordinary tendency of the pack to crumble anddeteriorate is greatly reduced.

The materials forming the cement mixture and their relative proportions,set forth herein as an example for carrying out the invention, aresubject to such substitutions and variations of proportions as skill inthe art a-ifords, and therefore, my invention is extensive thereto.

\Vhat I claim is l. A heating unit comprising a pack formed of a mixtureof refractory material, clay and boracic acid, and an electricalresistance member encased in the pack.

2. In an electrically heated unit having a resistance member, a packencasing the memloer and being composed of pulverulent refractorymaterial, clay and boracic acid.

In testimony whereof I afiix my signature, in presence of two witnesses.

' WILLIAM A. BRAUN.

Witnesses Zor: MUQKLEY,

WENGER.

